The present invention relates to a wheel bearing unit for vehicles having a device for determining the speed of rotation of the wheel.
Wheel bearing units are known which have at least one race which is developed as a hub, and which is provided with an attachment flange. For ease of assembly, at least one inner ring of a double-row angular anti-friction bearing of the wheel bearing unit is frequently manufactured separately, and is then installed on a shoulder of the hub. The hub also bears the other inner ring. After installation, the separately manufactured inner ring must then be fastened axially. Federal Republic of Germany Application OS 34 18 440 teaches fixing the separate inner ring in place with a bead formed by plastic deformation of the shoulder of the hub. The bead is provided opposite to the outer end side of the inner ring to axially fasten the inner ring.
Furthermore, in a vehicle using such a bearing, it is often necessary to determine the speed of rotation of the wheel for example, in connection with an anti-lock bearing system dependent upon wheel spin rate.
Prior art teaches providing the rotating bearing parts with a pulse ring. Interruptions on the pulse ring are situated opposite to a rotation detector which senses the speed of rotation. For example, one such embodiment is shown in "ATZ Automobiltechnische Zeitung", 90 (188) 3, page 116.
Such known wheel bearing units are, however, expensive and occupy too much space. In the known wheel bearing units, it is necessary to manufacture a separate pulse ring, and to mount it on the wheel bearing unit, at some added expense. Frequently, this approach also fails to provide the accuracy required in determining the speed of rotation. Moreover, the pulse ring in such an arrangement occupies additional space in the wheel bearing unit.
European Patent Application EP-323,159, discloses an automobile wheel bearing unit having a separate inner ring with projections directly and integrally formed on an end surface of the inner ring. In this case, however, the above-mentioned disadvantages of the prior art are present. For example, there is disturbance of the signals to the sensor by a nut and washer provided as attachment means to fix the inner ring to the wheel bearing unit. Moreover, the inner ring has a relatively complicated shape, which is technologically difficult to manufacture, and expensive to use in view of the special tools required for anti-friction bearings.